The field of the invention relates to new small molecules and uses of the new small molecules for modulating glucocerebrosidase activity. The new small molecules have a substituted 4-methylpyrrrolo[1,2-a]pyrimidine-8-carboxamide core structure, such as a 2,4-dimethylpyrrrolo[1,2-a]pyrimidine-8-carboxamide core structure, and the small molecules may be administered to treat diseases and disorders associated with aberrant glucocerebrosidase activity including neurodegenerative diseases, such as Gaucher's disease and Parkinson's disease.
Glucocerebrosidase (EC 3.2.1.45), which also is called β-glucocerebrosidase, β-glucosidase, D-glucosyl-N-acylsphingosine glucohydrolase, or GCase, is an enzyme having glucosylceramidase activity. Glucocerebrosidase is required to cleave the beta-glucosidic linkage of the chemical glucocerebroside, which is an intermediate in glycolipid metabolism. Glucocerebrosidase is localized in the lysosome and disabling mutations in the gene for glucocerebrosidase (GBA1) are associated with abnormal accumulation of lipids in lysosomes.
Genetic diseases caused by mutations in GBA1 include neurodegenerative diseases such as Gaucher's disease and Parkinson's disease. Gaucher's disease is a rare genetic disease caused by GBA1 gene mutations. Currently, the treatment for Type 1 Gaucher's disease is enzyme replacement therapy (ERT) administered every two weeks. ERT is very expensive and not effective for neuronopathic forms of Gaucher's disease. Mutations in GBA1 also are linked to Parkinson's disease (PD) by increasing the risk of PD. The so-called “pharmacological chaperone strategy” has been previously attempted in order to activate GCase. However, none of the compounds used in the pharmacological chaperone strategy were successful in activating GCase presumably because they targeted the active site of GCase.
Here, we disclose novel substituted 4-methylpyrrrolo[1,2-a]pyrimidine-8-carboxamide compounds which modulate glucocerebrosidase activity. The substituted 4-methylpyrrrolo[1,2-a]pyrimidine-8-carboxamide compounds disclosed herein have better chemical and physical properties than previous reported non-active site GCase inhibitors. (See Goldin et al., WO, “Substituted pyrazolopyrimidines as glucocerebrosidase activators.” December 2010, WO2012078855; and Patnaik et al., “Discovery, structure-activity relationship, and biological evaluation of noninhibitory small molecule chaperones of glucocerbrosidase,” J. Med. Chem. 2012 Jun. 28; 55(1′2):5734-48, the contents of which are incorporated herein by reference in their entireties). These better chemical and physical properties of the disclosed 4-methylpyrrrolo[1,2-a]pyrimidine-8-carboxamide compounds include polar surface area, solubility, increased number of rotatable bonds, and increased number of potential hydrogen bonding members. Some of the substituted 4-methylpyrrrolo[1,2-a]pyrimidine-8-carboxamide compounds in the present study are capably of highly activating GCase. For example, some of the substituted 4-methylpyrrrolo[1,2-a]pyrimidine-8-carboxamide compounds bind to GCase covalently and activate wild-type GCase up to 15-30 fold. GCase thus activated by the novel compounds is observed to be more stable in an acidic environment than non-activated GCase. Moreover, we found that the substituted 4-methylpyrrrolo[1,2-a]pyrimidine-8-carboxamide compounds can be conjugated to fluorophones to create pyrrolopyrimidine fluorescent probes which show strong binding affinity in fluorescence polarization assays. This suggests that these pyrrolopyrimidine fluorescent probes may be utilized in high throughput screening methods to identify further modulators of GCase activity.